Bottom Line:
The aim of the present study was to investigate the effect of cell fusion between mesenchymal stem cells and the gastric epithelial cells in tumorigenesis.Aneuploidy was observed in 84.1% of cells.These findings suggest that cell fusion between gastric epithelial cells and mesenchymal stem cells may result in epithelial to mesenchymal transition and malignant transformation.

Background: The discovery of cancer stem cells and tumor heterogeneity prompted the exploration of additional mechanisms aside from genetic mutations for carcinogenesis and cancer progression. The aim of the present study was to investigate the effect of cell fusion between mesenchymal stem cells and the gastric epithelial cells in tumorigenesis.

Methods: Cell fusion between cord blood mesenchymal stem cells and human gastric epithelial cells was performed in vitro. Cell scratch and transwell assays were performed to determine migration and invasion abilities of the hybrids. The expressions of epithelial-mesenchymal transition-related proteins and genes were analyzed by immunocytochemistry and real time quantitative PCR. Tumorigenesis of the hybrids was evaluated through in vivo inoculation in nude mice.

Results: Hybrids expressed the phenotypes of both donor cells. Aneuploidy was observed in 84.1% of cells. The hybrids showed increased proliferation, migration and invasion abilities compared with the parental cells. In addition, the expression of N-cadherin and vimentin in the hybrids was significantly higher than that of the epithelial cells, and the mRNA expression of the epithelial-mesenchymal transition-related genes, Twist and Slug, in the hybrids was also increased compared with that of the parental epithelial cells. Furthermore, the hybrids formed masses of epithelial origin with glandular structures in BALB/c nude mice.

Conclusions: These findings suggest that cell fusion between gastric epithelial cells and mesenchymal stem cells may result in epithelial to mesenchymal transition and malignant transformation.

Fig5: Subcutaneous injection of the hybrids. At 7 days after subcutaneous injection in BALB/c nude mice, no mass was observed in those injected with GES-1 (panel A) or CM-MSCs (panel B), but masses were observed in mice injected with hybrids (panel C). With prolonged observation time, GES-1 and CM-MSCs remained negative for subcutaneous masses, while the size of the masses decreased in mice injected with hybrids (panel D). H&E staining (panel E) and CK-18 IHC (panel F) results show that the masses were of epithelial origin and gastric gland structures were observed, but not show characteristics of malignant tumor. Magnification: 40×, Scale bar 200 μm. Data are representative of three experiments.

Mentions:
GES-1, CM-MSCs, and the hybrids were collected and 1 × 107 cells were injected subcutaneously into the armpit area of BALB/c nude mice (N = 8) and mice were observed for 4 weeks for tumor formation. At 7 days after injection, no mass was observed in those injected with GES-1 (Figure 5A) or CM-MSCs (Figure 5B), However, subcutaneous masses were observed in six of the eight mice injected with hybrids cells 7 days after injection (Figure 5C). With prolonged observation time, GES-1 and CM-MSCs group remained negative for subcutaneous masses , and the volume of four of the six masses observed for hybrids group decreased (Figure 5D). H&E staining (E) and CK-18 IHC (F) results showed that the masses were of epithelial origin and gastric gland structures were observed, but no characteristics of malignant tumor was found. This result indicated that the tumorigenicity potential of normal epithelial cells increased after fusion with MSCs, which suggests that cell fusion could participate in gastric cancer carcinogenesis.Figure 5

Fig5: Subcutaneous injection of the hybrids. At 7 days after subcutaneous injection in BALB/c nude mice, no mass was observed in those injected with GES-1 (panel A) or CM-MSCs (panel B), but masses were observed in mice injected with hybrids (panel C). With prolonged observation time, GES-1 and CM-MSCs remained negative for subcutaneous masses, while the size of the masses decreased in mice injected with hybrids (panel D). H&E staining (panel E) and CK-18 IHC (panel F) results show that the masses were of epithelial origin and gastric gland structures were observed, but not show characteristics of malignant tumor. Magnification: 40×, Scale bar 200 μm. Data are representative of three experiments.

Mentions:
GES-1, CM-MSCs, and the hybrids were collected and 1 × 107 cells were injected subcutaneously into the armpit area of BALB/c nude mice (N = 8) and mice were observed for 4 weeks for tumor formation. At 7 days after injection, no mass was observed in those injected with GES-1 (Figure 5A) or CM-MSCs (Figure 5B), However, subcutaneous masses were observed in six of the eight mice injected with hybrids cells 7 days after injection (Figure 5C). With prolonged observation time, GES-1 and CM-MSCs group remained negative for subcutaneous masses , and the volume of four of the six masses observed for hybrids group decreased (Figure 5D). H&E staining (E) and CK-18 IHC (F) results showed that the masses were of epithelial origin and gastric gland structures were observed, but no characteristics of malignant tumor was found. This result indicated that the tumorigenicity potential of normal epithelial cells increased after fusion with MSCs, which suggests that cell fusion could participate in gastric cancer carcinogenesis.Figure 5

Bottom Line:
The aim of the present study was to investigate the effect of cell fusion between mesenchymal stem cells and the gastric epithelial cells in tumorigenesis.Aneuploidy was observed in 84.1% of cells.These findings suggest that cell fusion between gastric epithelial cells and mesenchymal stem cells may result in epithelial to mesenchymal transition and malignant transformation.

Background: The discovery of cancer stem cells and tumor heterogeneity prompted the exploration of additional mechanisms aside from genetic mutations for carcinogenesis and cancer progression. The aim of the present study was to investigate the effect of cell fusion between mesenchymal stem cells and the gastric epithelial cells in tumorigenesis.

Methods: Cell fusion between cord blood mesenchymal stem cells and human gastric epithelial cells was performed in vitro. Cell scratch and transwell assays were performed to determine migration and invasion abilities of the hybrids. The expressions of epithelial-mesenchymal transition-related proteins and genes were analyzed by immunocytochemistry and real time quantitative PCR. Tumorigenesis of the hybrids was evaluated through in vivo inoculation in nude mice.

Results: Hybrids expressed the phenotypes of both donor cells. Aneuploidy was observed in 84.1% of cells. The hybrids showed increased proliferation, migration and invasion abilities compared with the parental cells. In addition, the expression of N-cadherin and vimentin in the hybrids was significantly higher than that of the epithelial cells, and the mRNA expression of the epithelial-mesenchymal transition-related genes, Twist and Slug, in the hybrids was also increased compared with that of the parental epithelial cells. Furthermore, the hybrids formed masses of epithelial origin with glandular structures in BALB/c nude mice.

Conclusions: These findings suggest that cell fusion between gastric epithelial cells and mesenchymal stem cells may result in epithelial to mesenchymal transition and malignant transformation.